Draw press



March 28, 1944. c. c. MISFELDT 2,345,353

DRAWPRESS Filed Aug. 4, 1941 v1?. Sheets-Sheet l IINVENTOR,

v '2. CHARLES c. M/SFELDT.

ATTORNEY.

Patented Mar. 28, 1944 UNITED STATES PATENT ounce 2,345,353 mmw muss Charles C. Misfeldt, Glendale, Calif.

Application August 4, 1941, Serial No. 405,314

18 Claims.

My inventionrelates to drawpresses, and more particularly to a drawpress which can be hydraulically controlled either manually or automatically.

Among the objects of my. invention are: To provide a drawpress in which the die bed ma be hydraulically and automatically elevated; to provide a drawpress capable of impartin to the work a. final forming and shaping impact; to provide a drawpress having a bed that can be progressively elevated as the drawing of the work proceeds; to provide a means and method of drawing metal sheets; and to provide a complete hydraulic control for a drawpress.

My invention possesses numerous other objects and features of advantage, some of which, together with the foregoing, will be set forth in the following description of specific apparatus embodying and utilizing my novel method. It is therefore to be understood that my method is applicable to other apparatus, and that I do not limit myself in any way to the apparatus of the present application, as I may adopt various other apparatus embodiments utilizing the method, within the scope of the appended claims.

In the drawings:

Fig. l is a view partly in elevation, partly in section, and partly diagrammatic of one form of drawpress embodying my invention, together with a hydraulic control therefor. Fi 2 is a fragmentary view showing the relationship of parts after a draw has been comleted. Referring directly to the drawings for a more detailed description of my invention, a press frame I is provided with a base block 2 and lateral uprights 33. Above the base block 2-is positioned an operating shaft 5 journaled in the upright 3, this operating shaft being driven from line shaft 6 through gears l and 8, the line shaft 8 being driven by a. motor I0. As is customary, gear I is clutched to shaft 5, under the control of a latch, not shown, which can be operated manually Or automatically to make one or more revolutions as desired, stopping at the top of the stroke. Line shaft 5 reciprocates through eccentrics II, male die plate I2 through connecting rods I4, die plate I2 being positioned by slides I5 bearing on uprights 3. Die plate I2 is adapted for the reception of a male die l6 which is at.-

tached thereto, and also supports a plurality,

preferably four, pressure pad cylinders I1 extending upwardly from die plate I2. Pressure cylinders I! are hollow and each is provided with an oil space I8 and an air space I9, these spaces being separated by a floating piston 20. Mounted to reciprocate in the 011 spaces I8 are movable pistons 2|, these pistons being attached to the pressure pad rods 22 extending downwardly through the die plate I2 and die I6, rods 22 being joined by a pressure pad 24.

Base block 2.15 centrally bored to provide a main piston chamber 30 in which is mounted a main piston 3|. Main piston 3| is provided with a top flange 32 on which rests a bolster plate 34 supporting female die 35. Bolster plate 34 and female die 35 are not solidly fastened on the top of main piston 3| but are merely positioned thereon by sliding pins 36 enterin recesses in the bolster plate 34 and female die 35 and extending through the top 3! of main piston ill to rest on a floating piston 3t. Floating piston 39 is movable through an airspace All in the top of main piston 3I, the airspace 40 being sealed from a main oil space 42 in main piston 38 by a separa-' tion plate 64.

Oil space 42 in main piston 3i contains a stationary piston 46. this piston 46 being supported on stationary piston column 4'! attached to base block 2, and this column therefore passes through the bottom of main piston 3|. Oil conduits 50 and 5! pass through column 41 from outside the press to terminate below and above the stationary piston 46 respectively. The bottom wall 52 of main piston 3i is provided with a plurality of air pockets 55, these air pockets being in downward connection with main piston chamber 3@.

Airspace so is provided with an air conduit 58 and main piston chamber 39 is provided with large connected oil conduits 5i. In much the same manner the oil spaces la in pressure pad cylinders H are provided with oil pipes 58. Airspaces IQ of the same cylinders are provided with air pipes lid.

I will next describe the illustrated hydraulic control circuit for the press. Oil conduits 50 and El opening on opposite sides of stationary piston 56 in base block 2 are connected to control pipes 6i and 52 respectively.

Control pipe 52, opening above the stationary piston 45 is connected first to a shut-01f valve 53 that is open and closed by action of a rod 64 reciprocated by a cam 65. Cam is connected by chain 56 to shaft 5 of the press, so that oil under pressure from main pump III with valve II in proper position can pass through four-way valve 1 I, and through main supply line 12 to the shutoff valve 63 via a metering valve 51.

The pressure from pump III is under strict regulation by the use of a pressure-regulating cylinder I5 provided with an airspace I6 and a pressure gauge 11. Main supply line I2 is also vented through a pressure release valve 89 into the main sump line 8I leading to sump 82 to safeguard against abnormal pressures in the main line. Line 6| goes directly to four-way valve II there to be connected either to sump line 84 or to pressure, in accordance with v'alve position.

The sump line 8| connects with main piston chamber 39 through large oil conduits 51 after passing from the sump through a pressure-open ated valve 83, this valve being normally closed and operated to open by pressure in line 6|.

On the 'piston side of valve 83 line 8I next passes through second shutoff valve 86 connected to rod 64 and operated with shut-off valve 63, both valves being connected to open and close at the same time under control of cam 65. Obviously rod 64 may be hand operated if desired. Oil in line 8| then passes through pressure switch 81 and thence directly into large conduits 51.

sure gauge 92 and through a pressure release valve 93 to four-way valve 95 which is supplied with oil from secondary pump 96 from sump 82.

' Pressure valve 95 also has a sump return 91 in one position of the valve to drain lines 99 and M. Thus by action of four-way valve 95, pressure pad 24 may be raised, lowered, or placed under any predetermined oil pressure as shown by the gauge 92. This completes the description of the bydraulic system,

The various airspaces mentioned are supplied from main air line I 99 under the control of main air valve I 9I through a pressure pad line I92 under the control of pressure pad valve I93 to airspaces I9 in pressure pad cylinders II.- Air is also supplied to airspace 49 in main piston 3| through line I94 under the control of main piston air valve I95.

In operation the dies are placed in position on the press, and adjusted as is customary for any drawing dies. A work sheet II9 of metal is then placed on female di which is in full downward position and with the male die I6 at the top of the stroke, oil is admitted to pressure pad cylinders I! to force the pressure pad 24 against the metal sheet I I9 and female die 35 to hold the sheet in position and with the proper pressure pad pressure. The press is then placed in operation by starting motor I9 and by pushing button 89 with the female die supported and cushioned by pressure in airspace 49, this space operating to cushion the die 35 through the medium of air piston 39 and pins 36, bearing on die 35. As the main shaft 5 of the press rotates it reciprocates male die I6, this die entering the female die a distance relatively short with respect to the total draw required of the press. During reciprocation pressure pads 24 will be maintained in contact with the work I I 9 because of the elasticity of the air in pressure pad cylinders I1. Thus the male die I6'can reciprocate, with the work held firmly between thepressure pad and the female die 35 during such reciprocation.

However, as reciprocation occurs cam 65 will sure.

be rotated, this cam operating both valves 65 and 63 to admit apredetermined amount of oil from pump 19 to the space above stationary piston 46 and to main piston chamber 39 thus raising the female die 35 a predetermined distance for every reciprocation of the male die I6, the female die being meanwhile cushioned by the pressure existing in airspace 49. Valves 63 and 86 are timed to be closed both at top and bottom of the stroke, so that at the time pressure is exerted against female die 35, main piston 3I is hydraulically locked. Oil for lifting is timed to enter on the up stroke only. I also prefer that the main die lifting pressure be applied by oil from line 62;

oil -in main piston chamber 39 being mainly for locking purposes.

As reciprocation continues the female die 35 will continue to move upwardly with a drawing increment imparted to the work at' each reciprocation of the male clie, until the male and female dies register. The final stroke of the .male die I6 can be made to impart a forming and setting impact to the work in accordance with the setting of pressure-release valve 81 which is in communication with main piston space 39. When the predetermined impact pressure is reached, the pressure switch 87 will operate to stop the press on the top of the next stroke. Thus a predetermined impact pressure may be given to the work after the final forming. As the press will stop with the male die at the top of the stroke following release of pressure switch and with automatic valves 63 and 64 closed, the next step is to return the female die to its lower position. This may be done by opening valves 63 and 64 by hand, and turning four-way valve II to apply oil pressure to line 6| opening beneath stationary piston 46. Oil above stationary piston 46 will drain into sump 82 through line 62, valve 63, valve II and sump-line 84. Oil in main piston chamber 59 will drain through conduit 51, valves 81 and 86, and through valve 83 into sump-line 8|, as valve 83 will be openedby pressure in line 6|. Thus the female die will be lowered by pres- It will also be obvious that for this latter operation valves II and rod 64 controlling valves 63 and 86 may be linked for simultaneous movement.

When the female die is lowered the drawn sheet is released by raising pressure pad 24, a new sheet inserted and the cycle repeated.

Thus the press I have described will not only impart to the work a succession of drawing increments, as predetermined by the setting of the metering valve 61, but is also capable of imparting to the work a final upsetting. impact, the pressure of which can be accurately regulated. In order, however, that the press may be protected from excessive pressures I have provided the bottom of main piston 3I with the trapped airspaces 54 downwardly connecting with main oil space 39. Air will at all times be trapped 'in spaces 54, so that if any extra heavy load is thrown on the press by failure of any part of the hydraulicsystem, the main piston 3i will not come elevated to a point from which-it recede.

It will also be noted that'as'the female di progresses upwardly, the pressure release val 93 which is connected tothe oil spaces I pressure pad cylinders illl, also allows oiltd'be drained from the pressure pad cylinder when a. predetermined pressure is reached in the cylinders. Thus no lock can occur in the pressure pad cylinders even though the amount of oil in the pressure pad cylinders is gradually reduced as the female die progresses upwardly. The action of airspaces l9 maintains the pressure pad in contact with the work.

Thus it will be seen that I have provided an automatic drawpress which will, under automatic operation, impart to the Work a series of pro gressively increasing draws during continued reciprocation of the male die member. Furthermore, at the end of the draw, a carefully regulated impact can be given to the work. Means are provided to safeguard the operation of the press at all times and toprevent disastrous results that might occur if the female die should be raised above the proper level. Furthermore, during the entire operation of the device cushioning of the dies takes place oven though pressures are progressively rising.

I claim:

1. In combination with a forming press having means thereon for imparting to a press die continuous cyclic strokes of uniform length, a bed for said press comprising a bed plate for holding a bed die mating with said press die, and hydraulic means for moving said bed toward said press die along the line of stroke of the latter during operation thereof.

2. In combination with a forming press having means thereon for imparting to a press die cntinuous cyclic strokes of uniform length, a bed for said press comprising a bed plate for holding a bed die mating with said press die, hydraulic means for moving said bed toward said press die along the line of stroke of the latter during operation thereof, means for controlling the movement of said hydraulic means, and a control for determining the extreme upward position of said bed.

3. In combination with a forming press'having means thereon for imparting to a press die continuous cyclic strokes of uniform length, a bed for said press comprising a bed plate for holding a bed die mating with said press die, hydraulic means for moving said bed toward said press die along the line of stroke of the latter during operation thereof, means for controlling the movement of said hydraulic means, and means for stopping the upward motion of said bed when said dies have mated a suillcient distance to upset metal between said dies on the final stroke of said press die.

a. Apparatus in accordance with claim 1 when said hydraulic means is a piston operated in a cylinder by an incompressible liquid under the control of a valve.

5. In combination with a forming press having means thereon for imparting to a press die continuous cyclic strokes of uniform length, a bed for said press comprising a bed plate for holding a bed die mating with said press die, and means for gradually moving said bed with a metal piece to be formed between said dies, toward said die and in mating alinemcnt of said dies, during operation of said press, until said dies mate a sufficient distance to upset the metal piece being formed.

6. Apparatus in accordance with claim 1 wherein a hydraulic valve is provided together with means synchronized with the stroke of said press die for operating said valve to admit fluid to said hydraulic means.

7. Apparatus in accordance with claim, 1 wherein a hydraulic valve is provided together with means synchronized with the stroke of said press die for operating said valve to admit a predetermined amount of fluid to said hydraulic means at each stroke of said press die to raise said bed die.

8. Apparatus in accordance with claim l'wherein a hydraulic valve is provided together with means synchronized with the stroke of said press die for operating said valve to admit a predetermined amount of fluid to said hydraulic means at each stroke of said press die to raise said bed die, and means releasing pressure in said hydraulic means after a predetermined pressure is exerted against said bed die by said press die.

9. In combination witha forming press having means thereon for imparting to a press die continuous cyclic strokes of uniform length, a bed plate attached to said press, a main piston operating in a recess in said bed plate, a stationary piston attached to said bed plate and operating in a recess in said main piston, hydraulic circuit means for supplying liquid under pressure to the recess in said main piston to move said main piston toward said press die, and a lower die mounted on said main piston.

10. Apparatus in accordance with claim 9 wherein means are provided to supply liquid to said bed plate recess as said main piston moves upwardly, and means for preventing the return of said latter liquid. 1

11. Apparatus in accordance with claim 9 wherein means are provided to supply liquid to said bed plate recess as said main piston moves upwardly, and means for preventing the return of said latter liquid for forming a hydraulic lock for said main piston. said main piston having trapped air spaces of predetermined size exposed to said latter liquid.

12. Apparatus in accordance with claim 9 I whereina pressure pad is provided movable with said press die, and hydraulic means for moving said pressure pad with relation to said press die.

13. Apparatus in accordance with claim 9 wherein a pressure pad is provided movable with said press die, and hydraulic means for moving said pressure pad with relation to said press die, said latter hydraulic means comprising a plurality of hydraulic cylinders mounted to move with said press die, and a plurality of pistons operating in said cylinders and attached to said pressure pad. 14. Apparatus in accordance with claim 9 wherein a pressure pad is provided movable with said press die, hydraulic means for moving said pressure pad with relation to'said press die, said latter hydraulic means comprising a plurality of hydraulic cylinders mounted to move with said press die, and a plurality of pistons operating in said cylinders and attached to said pressure pad, each of said cylinders having a trapped airspace therein.

15. Apparatus in accordance with claim 9 wherein a pressure pad is provided movable with said press die, hydraulic means for moving said pressure pad with relation to said press die, said latter hydraulic means comprising a plurality of hydraulic cylinders mounted to move with said press die, and a plurality of pistons operating in said cylinders and attached to said pressure pad, each of said cylinders having a trapped airspace therein together with means for changing the air pressure in said latter spaces.

16. The method of forming a sheet metal blank which comprises placing said blank between dies,

cyclically reciprocating one if said dies with a uniform length of stroke, and moving the other die in successive increments timed with the strokes of said first die, toward said first die during continuous reciprocation thereof.

17. The method of forming a sheet metal blank which comprises placing said blank between dies, cyclically reciprocating one of said dies with a uniform length of stroke, moving the other die in successive increments timed with the strokes of said first die, toward said first die during continuous reciprocation thereof, and terminating the movement of said other die after forming is com- 18. The method of forming a sheet metal blank which comprises placing said blank between dies, cyclically reciprocating one of said dies with a uniform length of stroke, moving the other die in successive increments timed with the stroke of said first die, toward said first die during continuous reciprocation thereof, terminating the movement 01' said other die after forming is complete at a point where a setting impact is given to the formed blank, and cushioning one of said dies at a setting impact pressure to prevent damage to said press.

plete at a point where a setting impact is given to the formed blank.

CHARLES C. MISFELDT. 

